Anthropic
Connect Sythoria to Anthropic's API to chat with the Claude family of models. Claude excels at nuanced reasoning, long-context understanding, and careful instruction following.
Prerequisites
- An Anthropic Console account
- An API key from the Anthropic dashboard
Setup
- Go to console.anthropic.com
- Click Create Key and copy it
- In Sythoria, open Settings from the sidebar
- Select Anthropic from the Provider Preset dropdown — the API base URL and default model fill in automatically
- Paste your API key into the API Key field
- The connection indicator should turn green within a few seconds
Your API key is stored securely in your OS keychain. It is never sent to Sythoria's servers. See Privacy & Security.
Default configuration
| Setting | Value |
|---|---|
| API Base | https://api.anthropic.com/v1/messages |
| Default Model | claude-opus-4-8 |
| API Format | Anthropic Messages API (Sythoria handles translation automatically) |
| Streaming | Supported |
Available models
| Model ID | Best for | Context window |
|---|---|---|
claude-3-5-sonnet-latest | Balanced performance — everyday tasks, coding, analysis | 200K |
claude-3-5-haiku-20241022 | Fast, lightweight responses — quick Q&A, simple tasks | 200K |
claude-3-opus-latest | Most capable — complex reasoning, research, long documents | 200K |
Important: API format differences
Anthropic uses a different API format from OpenAI (the Messages API vs. Chat Completions). Sythoria handles this translation automatically — you don't need to worry about message formatting, role mapping, or streaming protocol differences. Just select Anthropic as your provider and chat as normal.
Pricing
Anthropic charges per token based on input and output size. Check anthropic.com/pricing for current rates. New accounts often receive free credits to get started.
Switching models mid-conversation
Use the model dropdown in the chat input bar to switch between Claude Sonnet, Haiku, and Opus without losing your conversation. Each new message uses the currently selected model.
Troubleshooting
| Error | Cause | Fix |
|---|---|---|
| 401 Unauthorized | API key is invalid or expired | Generate a new key at console.anthropic.com |
| 429 Rate Limit | Hit your usage tier's rate limit | Check your console for limits, or wait a moment and retry |
| 400 Bad Request | Message format issue | Sythoria handles formatting automatically — if this persists, try starting a new conversation |
| Connection indicator red | Network issue or invalid API base | Verify the API base URL is https://api.anthropic.com/v1/messages and click Refresh |
